’m telling ya, there are few audio components that move music lovers and audiophiles’ hearts as much as those from Jeff Rowland. The components manufactured in Colorado Springs have a look that cannot be mistaken for anything else, and their build quality beats almost everything else in the audio world. Their distinguishing mark is their front and top panel wavy pattern finish difficult to confuse with anything else. It's an optical illusion, but an extremely convincing one. Only one other company used to have a similar, equally well-made faceplates – Enlightened Audio Design, a no longer existing American home theater specialist. Those people, now working at Noble Electronics, were fantastic in what they’re doing. Their components’ faceplates were made – no surprise there – by Jeff Rowland. Actually, Jeff Roland was the middleman as the enclosures were manufactured by a specialized firm Vertec Tool from Colorado Springs.

Attention to every last detail, almost obsessive, goes hand in hand with carefully selected design solutions, highly rated by Jeff, some of which are controversial in the audio world. To give an example, although it is not the case with the 625 under review, JR lesser amplifiers employ class D topology. And what about the 625? It is built on LME49810 integrated drivers driving discrete power transistors. On top of that, all components from this manufacturer are equipped with switching power supplies, rated very negatively by many. Linn, Chord, and now Soulution have proven that the problem was not with them but with their proper application. And, last but not least, the ubiquitous coupling transformers – every JR component sports at least a pair of them in the left and right channels, and sometimes more. They are used to couple balanced outputs or as interstage coupling. ICs abound throughout and discrete transistors are only used in the power output stage. The reason is that Jeff Rowland opts for minimalist approach – his designs employ an ultra-short signal path and minimum number of electronic components. No, this manufacturer cannot be mistaken for any other.
To see it in action, I asked for an entire system to review: the Aeris DAC, one of the two preamplifiers named Corus and the 625 stereo power amplifier The latter, prepared for Jeff Roland’s 25th anniversary, is also available as 725 monoblocks.

Audio is the art of compromise – that much is clear. However, it’s important to understand that we face compromises both on the manufacturer’s side and on our own. In the classical theory of language, the manufacturer would be the sender of the message and the music lover or audiophile – whatever we call him – its receiver. But that's not all. This basic level of information exchange is overlapped with another. On the basis of the communication between the manufacturer that "programs" his products in his own way to achieve specific results, and the music lover who has his own expectations and preferences and responds in his own way to the sender’s offer, another level is applied – that of the music, with the Sender (artist, sound engineer, producer) and the Recipient (music lover, audiophile). This second pair starts with uppercase as it is the one that is most important. What’s interesting is that the arrival point is the same in both cases. The receiver/ Recipients is US. That’s why it’s so difficult to reach a consensus – the listener must define himself in the context of his expectations with regard to the music and to the medium through which the music is conveyed, that is the audio system. He has to decide whether and to what extent the music presentation can be modified – and how – and still be acceptable to him.
This short introduction is needed to show you how well Jeff Rowland understood these relationships and to draw your attention to the fact that his choices and decisions were informed and well thought out. There is no other way to achieve what we get with the system under review. It doesn’t happen by chance or by copying existing solutions, or even through a flash of inspiration. It comes as the result of long, hard work.
The sound of the reviewed system can be described briefly but accurately as refined. The overall impression was virtually identical, both when I sat down to it for the first time, spinning the first disc and learning its sonic characteristics, and when I got up after the last album to pack up the system and return it after the review. A lot happened "in between", of course, to help me better understand the nuances and appreciate them but the overall message that I, as a customer, received from Jeff Rowland was clear.

The sound was smooth, soft, and vivid while at the same time very deep and well differentiated. While its main dominant is the pursuit of refinement rather than perfection, the scale of differentiation was puzzling. If I were to draw analogy I would compare this presentation to that of the Harbeth M40.1 speakers. Warm and rather nice at first, after a while they turn out to be incredibly resolute. And not as selective as I would wish.
First, however, let’s talk about resolution and differentiation. Warm sounding components and speakers are usually associated, and rightly so, with a not particularly good selectivity and rather low resolution. This is true as long as we stay within the basic and medium price ranges. Good designs costing about 20,000 PLN and more are much more varied and nuanced in this respect. Listen to the Lavardin IT-15 amplifier to know what I mean (see HERE). In the top high-end where we are with Jeff, these are completely unrelated to each other. Unless the designer intended – as with the Convergent Audio Technology SL1 Legend (see HERE) preamp – to emphasize warmth as the leading and most important aspect of a live sound. The reviewed system seems to follow a similar suit. The point of arrival is different, though.
Take for instance the way it differentiates various albums and recordings, or even within a single track rivets us to the speakers. It doesn’t do it through an incredible amount of detail or the kind of dynamics and insight into the recording that knocks us down to the ground. At least not at first glance. It does it through a "clear" resolution or in other words the ability to show the maximum amount of details per time unit, internally linked and creating something beyond themselves. It's the kind of sound that doesn’t require an effort to reconstruct in our mind what took place in front the studio microphones. Hypothetically and potentially, of course, as we were not present during the recording yet very credibly, despite these reservations. No need for super-audiophile recordings to hear that, no need to reach for Patricia Barber’s albums, although they were also auditioned. It’s not necessary to use special re-editions, such as XRCD24 discs from the newly created Hi-Q Records, where sound production is handled by Mr. Kazuo Kiuchi, owner of such brands as Reimyo and Harmonix. I did audition one of them, Bach’s Violin Concertos performed by Yehudi Menuhin.

My biggest surprise was listening to the new Black Sabbath album 13. While it’s pressed as SHM-CD, the material is intended for a wide audience and hence highly compressed. First I listened to it at night, on my HiFiMAN HE-6 headphones driven from the amplifier current output, and even then I was struck by a great clarity with which Ozzy Osbourne vocals and Tony Iommi guitars were recorded and mixed. I use plural “guitars” as Tony’s guitar is overdubbed and often doubled, with lots of spatial sound effects. The tonal balance was really well set without using the proven "patent" of "wall of sound" that covers playback and recording mistakes. The sound was powerful, fleshy, but also selective. On these particular headphones drums seemed somewhat lacking, though, especially the bass drum. Rowland’s system tastefully showed what was going on. It served a very low, punchy bass, and when kettledrums appeared in the beginning of God is Dead? they were conveyed very vividly but also fast, with a rapid attack, good body and depth. Similarly, Geezer Butler’s bass guitar was super-fleshy. Now, despite adding additional elements, the sound was neither blurred nor veiled. While Mr. Fang Bien’s magnetostats had seemed made for showing attacks and fast transients which could have added some clarity to the material on the Sabbath disc, nothing like that happened. The allegedly warm Harbeths driven by the allegedly warm Rowland confirmed what I heard on the headphones, adding to that more body and fantastic volume.
On the other end of spectrum, with the music quieter by a few generations, recorded between 1932 and 1939 and included on the reissues of Mills Brothers recordings, I felt something even more tangible. It was as if the American system turned a better recording into a true music event. I listened to tracks from the two compilations – coming from the History series of Trumpets Of Jericho label Swing Is The Thing and Spectacular released by Going For A Song. The former had been remastered in the digital domain, with no further details how it had happened, and the latter had been made in the CEDAR system. The source in both cases were old, shellac discs. The latter was without any doubt spectacular. It had a warm sound, not only due to appropriate tone correction but also a better volume and depth. The former, while every bit correct, sounded flat and boring.

Despite the impression - I'll come back to that because it's leitmotiv – of sounding warm and sweet, the Rowland system allows for such introspection. It does it casually, without being pushy. Everything I wrote is picked up along the music. It’s really addictive. The more so as with acoustic music, played without amplification, like on Clifford Brown’s Memorial or John Coltrane's A Love Supreme the presentation of bass and treble was different. At first, the cymbals and double bass seemed withdrawn. But only for a while, until something changes and we get to the place where the bass instrument is stronger, amplified by the studio walls and microphone. Then it sounds naturally and not exaggerated. But even when it’s not there we don’t hear a "hole". The sound is not dry or shallow, as if there was an “air cushion" under the midrange, containing potential information about the instrument.

The dynamics was very good, but it’s here that it’s audible something had to be "trimmed" and sacrificed. The Soulution amp is much more open and faster, giving us not only the impression of a strong attack, but also its sheer physical power right in front of us. The American system does it softer and in a more studied manner. It's this lack of spontaneity that probably needs to be taken into consideration while analyzing our needs and expectations regarding audio components.

Conclusion

I have no doubt that in the Sender – Receiver relationship the Jeff Rowland is excellent and has its own personal charm. It conveys the music in a very refined, thoughtful and mature way. At the same time the sender, this time with a small “s”, communicates to us the limitations of the applied solutions and decisions. If we need the ultimate dynamics and tangibility of sound, not in terms of its size and proximity but of texture clarity, today’s system will not be the best choice. In this case, such – far apart ideologically – amplifiers as the Soulution 710 (I haven’t yet heard the new 711) and the Ancient Audio Silver Grand Mono (see HERE ) will prove a better choice. If, however, we are more concerned with the color saturation, the Jeff Rowland comprising the Aeris DAC, the Corus and the 625, will be perfect. It will be a choice that’s both safe and definitive. While neither of the above machines, the Polish and the Swiss amps, can be accused of the lack of color, the American trio slightly tweaked in this regard will beat them easily.
As usual, it is a difficult, very personal and long-lasting choice. Seen in person and listened to at leisure, the American components will leave in our minds something like a "cookie" on our computer, to which we will come back and which will remind us of itself on every other occasion. Perhaps it will be easier just to buy them. While other people are stuck with "cookies" in their minds, we will be listening to music.

Jeff Rowland is best known for its amplifiers (and preamplifiers). Since computer related sources came into play, DACs have also become increasingly important. The AERIS DAC is the only such product offered by this manufacturer. It was part of the system under review, together with other Rowland components – the Corus preamplifier and the 625 power amplifier. That was how I conducted auditions that had the character of an A/B/A comparison, with the A and B known. The point of reference was my reference system. The Jeff components were coupled with the Acoustic Revive cables from the System II (see the description of the reference system). The DAC was fed digital signal off the Ancient Audio Lektor Air V-edition sporting the Philips CD-Pro2LF transport via the Oyaide DB-510 digital interconnect with BNC connectors. Although the DAC came equipped with get an RCA adapter that makes possible using an RCA to RCA digital cable, I wanted to avoid that. I used a reverse adapter of this type (from Stereovox) on the CD player side. USB connection was via the Acoustic Revive USB-5.0PL (5 m) cable from my HP Pavilion dv7 laptop (SSD 128GB + HDD 320GB, Windows 8 Pro x64) running the latest version of JPLAY audio player. AERIS USB input is limited to 96 kHz. To play 176.4 kHz and 192 kHz files I had to use the USB-S/PDIF M2TECH hiFace EVO external converter with the EVO battery supply (see HERE).
The DAC sat on the Franc Audio Accessories Ceramic Disc feet with the Acoustic Revive RIQ-5010/CP-4 quartz insulators. The preamplifier sat on its own feet and was placed on the Acoustic Revive Hickory Board RHB-20. The amplifier sat on the HRS M3X platform (see HERE). The amplifier was powered via its own power cord as I don’t have one with 20 A plugs which are required for the 625.

Jeff Rowland Design Group made build quality its own personal religion. Jeff Roland components are housed in very expensive, sophisticated enclosures which are precision machined from a single block of 6061-T6 aircraft grade aluminum and sport very thick, unique faceplates. The latter are silver finished in a special laser process to give their surface a wavy look. While it may sound a tad cheesy, their appearance is nothing like that.

Aerius DAC

DAC is the smallest unit of the three. The low front fascia sports a row of buttons and LEDs in different colors.
The manufacturer lists a number of concepts employed in the Aeris design. Worth mentioning are jitter reduction systems (quoted to reduce total jitter to less than 10 picoseconds RMS) and IsoSyncESC or Isolated Synchronous Error Correction System, based on an asynchronous buffer controlled by a precise clock and employing an FPGA running proprietary algorithms. While not mentioned explicitly, it seems to be a kind of proprietarily executed asynchronous upsampling. Analog and digital sections as well as left and right channels and digital processing circuits are isolated from each other within individual milled aluminum pockets. Power supply is isolated inside an external machined aluminum chassis. High-precision SMD components are mounted on 6-layer circuits boards. XLR line outputs are transformer coupled.

Let’s stop, however, at the front panel. We see here several groups of buttons and LEDs. The first button group comprises an input selector to choose between TOSLINK, one of the two BNC and USB. The first three receive signal up to 24/192; the USB port is limited to 96 kHz. This eliminates the need for driver installation but won’t let us play 192 kHz audio files. To do that, we need an external USB-S/PDIF converter connected to one of the BNC inputs. Blue LEDs indicate the input selected. Next to them, we have a standby button with an orange LED. It is followed by a row of green LEDs indicating input signal sampling frequency. Below are two LEDs that signal establishing a link with the source and non-standard signal sampling rates, respectively. Next we have a mute button with a red LED and two volume control buttons with blue LEDs. The Aeris is capable to drive a power amplifier directly, as its maximum output voltage is 7 V. When using a preamplifier, the DAC output level needs to be attenuated to avoid input overload. The manufacturer claims that this doesn’t degrade the sound quality as the Aeris volume control is neither purely analog nor digital. Instead, it is implemented by varying the reference current in the DAC chip.
The rear panel makes a great impression, confirming that we deal here with a perfect enclosure design. The analog rhodium-plated copper connectors come from Cardas. They use Teflon dielectric and look superb. The BNC connectors are gold plated. Only the USB port looks ordinary. Next to it is a multi-pin SC8 connector from Neutrik. It is used to connect the external power supply housed in a chassis as solid as that of the DAC. Looking inside, it turns out to be a switching power supply, or actually two separate supplies for the digital and analog sections. All components in this review are powered by switching power supplies.

DAC’s interior explains the unit’s substantial weight – to pick it up is like lifting a metal block. That is not far off the mark as the chassis is machined from a solid block of aluminum with milled out pockets housing electronic circuits and cables. Electronic circuit is mounted on a small PCB. The USB input is on an old TAS1020 chip, well-known for years. But this is a special that was programmed by Gordon Rankin from Wavelength Audio. It works in an asynchronous mode and is known for its excellent sound. The S/PDIF inputs feature coupling transformers. The signal from the selected input is sent to a Xilinx Spartan DSP with an asynchronous buffer for jitter reduction. Next to it are two small crystal oscillators, separately for 44.1 kHz and 48 kHz based sample rates.
From there we get to the D/A converter on a single AD1853 chip from Analog Devices. The whole analog circuit is built on L49990 opamps – six per channel. These are ultra-low distortion, low noise, high slew rate Overture E-Series operational amplifiers. The output is switchable via relays and XLR outputs are buffered in Lundahl transformers. The signal sent to the output jacks is short kabelkami.

The DAC comes with a remote control. It's a beautiful, heavy chunk of machined aluminum sporting small control buttons. IR receiver is placed rather unconventionally under the unit’s bottom panel and is visible from the front. The remote duplicates the control functions available from the front panel.

Corus

The preamplifier is larger than the DAC but still not large. Unlike the DAC, its user interface features a large, white VFD display. Control buttons are placed below and include input and record source selectors, menu, display off and mute. Next there is a classic, if small, volume control knob, which for me is far more convenient to use than buttons. The really nice and clear display presents us with lots of information. Large digits show volume level in 0.5 dB increments. An adjacent bar graph displays channel balance while the currently selected input is shown above. The input names can be changed. We also get information about which source is routed to the record output.
The rear panel looks very impressive. It sports an ample amount of inputs in the form of four XLR balanced and two RCA unbalanced pairs. Unfortunately, the XLR connectors are not from Cardas. They are classic, solid Neutriks with gold plated pins. All the RCA connectors seem to be Cardas-made, though. The inputs are complemented with two pairs of XLR + RCA line outputs and a record output, also on XLR and RCA. In the center there are two multi-pin sockets to connect the external power supply. The latter is as superbly finished as the DAC’s PSU, except that it sports two output connectors. It actually houses two separate power supplies to separately connect and power the left and right channels. And there's one little connector in the bottom. Unlike with the DAC, an IR receiver needs to be connected for remote control. This features an equally solid aluminum housing as the handheld remote.

The Corus chassis is a machined block of aluminum. The whole interior is milled out, leaving only thick screen walls between the input and gain sections. The latter is truly unique and features an ultra-short signal path. I could only identify two TI Burr-Brown OPA1632 opamps and three Burr Brown PGA 23201 volume control chips – one for each of the line outputs, A and B, and the record output (yes, its level can be adjusted separately). The signal path also features Lundahl coupling transformers in the input and output stages. Input switching is logic controlled. That's it. This must be the most minimalist active preamplifier I have yet seen.

625

Nothing focuses Jeff Rowland’s obsessions and "inner demons" as much as its power amplifiers. Once battery powered (yes!), they now feature sophisticated multi-stage switching power supplies. Their chassis is milled from a single aluminum billet, with characteristic heat sinks. The latter are needed to cool down 625’s six pairs of Sanken Darlington modules (STD03N + P) in push-pull configuration per channel. Premium circuit components include ultra-precision Dale resistors. Ground lines incorporate gold plated copper bus bars. The input stage features Lundahl coupling transformers as the amplifier only accepts a balanced signal. Interestingly, right in the center, four LME49810 integrated audio power amps from National Semiconductors – two per channel due to a balanced topology – are mounted to a small section of the chassis. These are designed to work as power amp drivers and when used with a discrete output stage can deliver up to 300 W at 4 Ω. Mystery solved… The gain section is assembled on a large circuit board. Underneath, separated by a thick screen, is a power supply board. Everything is beautifully assembled. I’ve already mentioned the inputs on single Neutrik XLR connectors. Let’s add to it that the speaker outputs are two pairs of superb Cardas speaker terminals designed for spade connectors.
The amplifier sits on three small feet in the shape of balls. The whole finish is insanely good.